This invention relates to inkjet printing systems. In particular, the present invention is a pigmented ink delivery system that employs filter fluid interconnects to fluidly interconnect separable ink delivery system components. The filter fluid interconnects function to provide reliable fluid interconnects between ink delivery system components, such as ink supply containers, inkjet printheads and ink manifold structures of an ink container receiving station. The screen filter fluid interconnects also prevent drooling of ink when ink delivery system components are separated, prevent clogging of the pigmented ink delivery system, and impede the passage of debris and air bubbles from the ink supply containers to the printheads.
Throughout the business world, inkjet printing systems are extensively used for image reproduction. Inkjet printers frequently make use of an inkjet printhead mounted within a carriage that is moved back and forth across print media, such as paper. As the printhead is moved relative to the print media, a control system activates the printhead to deposit or eject ink droplets onto the print media to form images and text. Such systems may be used in a wide variety of applications, including computer printers, plotters, copiers and facsimile machines.
Ink is provided to the printhead by a supply of ink that is either integral with the printhead, as in the case of a disposable print cartridge, or by a supply of ink that is replaceable separate from the printhead. One type of previously used printing system makes use of an ink supply that is carried with the carriage. This ink supply has been formed integral with the printhead, whereupon the entire printhead and ink supply are replaced when ink is exhausted. Alternatively, the ink supply can be carried with the carriage and be separately replaceable from the printhead. As a further alternative, the ink supply can be mounted to the printing system such that the ink supply does not move with the carriage. For the case where the ink supply is not carried with the carriage, the ink supply can be in fluid communication with the printhead to replenish the printhead or the printhead can be intermittently connected with the ink supply by positioning the printhead proximate to a filling station to which the ink supply is connected whereupon the printhead is replenished with ink from the refilling station. Generally, when the ink supply is separately replaceable, the ink supply is replaced when exhausted. The printhead is then replaced at the end of printhead life. Regardless of where the ink supply is located within the printing system, it is critical that the ink supply provides a reliable supply of ink to the inkjet printhead.
Inkjet printing systems typically employ either dye based inks or pigmented inks. In dye based inks, the ink color is in solution and defines the ink itself. As such, dye based inks readily remain in solution. In pigmented inks, the ink color is defined by particles suspended in a carrier fluid. As such, in pigmented inks, the ink color particles can fall out of suspension (i.e., flocculate) or the carrier fluid can evaporate off leaving the ink color particles behind. These conditions are not as pronounced in dye based inks, since dye based inks easily remain in solution, and if the ink color of dye based inks does settle out, the ink color readily goes back in suspension. In ink delivery systems that use dye based inks, a fluid interconnect, employing a fluid delivery tower having a filter, is used to fluidically couple separable ink delivery components, such as ink containers, printheads and a carriage manifold.
The filter of the filter/tower fluid interconnect allows passage of the dye based ink when the ink delivery system is operating, and prevents ink drooling when the ink delivery components are disconnected. In addition, the filter of the filter/tower fluid interconnect can impede the passage of air bubbles and particulate matter to the ink delivery tower and ultimately to the print element of the printhead. If bubbles and particulate matter enters the print element, they can block the ink delivery channels, conduits, chambers, orifices and ink ejection nozzles of the print element, thereby adversely affecting printhead performance. This clogging is likely to result in one or more inoperable firing chambers within the printhead, which would require that the clogged printhead, be replaced with a new printhead before the useful life of the clogged printhead is exhausted. From the perspective of cost, this course of action is undesirable. In addition to providing filtering benefits, the filter/tower fluid interconnects used with dye based inks are economical to manufacture.
In pigmented ink delivery systems, flocculation and evaporation of carrier fluid becomes a particular problem when a user disconnects the separable ink supply containers and/or printheads from the carriage manifold. At this time, fluid interconnects between the ink containers, printheads and carriage manifold are exposed to the atmosphere, and the carrier fluid at the fluid interconnects can quickly evaporate off leaving behind ink color particles that may clog these fluid interconnects. In addition to evaporative based clogging, if the containers, printheads and carriage remain in a sedentary state for too long, the ink color particles can settle out of the carrier fluid also resulting in clogging of the fluid interconnects. As such, ink delivery systems that use pigmented inks, do not use filter/tower fluid interconnects since the filter can become easily clogged upon evaporation of the carrier fluid or when the ink color particles settle out of the carrier fluid. Moreover, ink delivery channels associated with the fluid interconnect can become clogged with pigmented ink viscous plugs due to liquid bridging. Therefore ink delivery systems for pigmented inks typically employ higher cost (when compared to filter/tower fluid interconnects) needle/septum fluid interconnects that can easily dislodge or break up pigmented ink clogs as the needle pierces the septum.
There is a need for improved fluid interconnects for components of ink delivery systems. In particular, there is a need for a filter/tower fluid interconnect that is not susceptible to pigmented ink clogs caused by the ink color particles falling out of suspension (i.e., flocculation) or the carrier fluid evaporating off leaving the ink color particles behind. Moreover, ink delivery channels associated with the filter/tower fluid interconnect should not be susceptible to clogging caused by pigmented ink viscous plugs as a result of liquid bridging. In addition, the filter/tower fluid interconnect should prevent pigmented ink drooling (i.e., leakage) at ink outlets and inlets when separable ink supply containers and printheads are disconnected from a carriage manifold. Further, the filter/tower fluid interconnect should impede debris and air bubbles from clogging or otherwise restricting the flow of pigmented ink from an ink reservoir of an ink container to a print element of a printhead. The filter/tower fluid interconnect should reliably provide these features throughout the useful life of the pigmented ink delivery system components so as to preclude premature replacement of these components and the associated cost. Lastly, the filter/tower fluid interconnect should be relatively easy and inexpensive to manufacture, and relatively simple to incorporate into components used in pigmented ink delivery systems of thermal inkjet printing systems.
The present invention is a pigmented fluid delivery system. The pigmented fluid delivery system comprises a first component and a second component. The first component has a fluid outlet in fluid communication with a supply of pigmented fluid. The second component has a fluid inlet releasably connectable to the fluid outlet of the first component. The fluid inlet includes a filter compatible with the supply of pigmented fluid.
In one aspect of the present invention, the pigmented fluid is defined by particles suspended in a carrier fluid, and the filter is an open weave screen defining a plurality of pores. The pores are sized to allow passage of the pigmented fluid while preventing clogging from flocculation of the particles and evaporation of the carrier fluid. In addition, the pores are sized to retain pigmented ink (i.e., prevent drooling) when the first and second components are disconnected. In a further aspect of the present invention, each pore of the plurality of pores has an edge-to-edge dimension of 200 xcexcm, and a depth dimension of 170 xcexcm which is perpendicular to the edge-to-edge dimension. In another aspect of the present invention, each pore of the plurality of pores has an edge-to-edge dimension of 106 xcexcm, and a depth dimension of 70 xcexcm which is perpendicular to the edge-to-edge dimension. In still another aspect of the present invention, the fluid inlet of the second component includes a cylindrical tower having an upstream end to which the filter is mounted and an opposite downstream end. A cylindrical channel extends perpendicular to the tower, and is in fluid communication with the downstream end of the tower. The channel has a diameter of 2.0 mm. In still a further aspect of the present invention, the first component is a replaceable fluid container, and the second component is a replaceable printhead. In yet another aspect of the present invention, the ink delivery system includes a third component having a fluid inlet releasably connectable to a fluid outlet of the second component. The fluid inlet of the third component includes a filter compatible with the supply of pigmented fluid. In this aspect of the present invention, the first component is a replaceable fluid container including a reservoir containing the supply of pigmented fluid, the second component is a manifold adapted to removably receive the replaceable fluid container, and the third component is a replaceable printhead adapted to be removably received by the manifold.
In another embodiment, the present invention provides a fluid interconnect. The fluid interconnect includes a tower member adapted to be connectable to a supply of pigmented fluid defined by particles suspended in a carrier liquid. A screen is mounted to the tower member. The screen defines a plurality of pores sized to allow passage of pigmented fluid from the supply of pigmented fluid, and sized so as to prevent clogging due to flocculation of the particles and evaporation of the carrier fluid.
In a further embodiment, the present invention provides a printer component. The printer component comprises a housing that includes a fluid inlet. The fluid inlet is releasably connectable to a supply of pigmented fluid. The fluid inlet includes a filter defining a plurality of pores sized to allow passage of pigmented fluid from the supply of pigmented fluid, and sized so as to prevent clogging due to flocculation of the particles and evaporation of the carrier fluid.
The filter/tower fluid interconnect of the present invention is not susceptible to pigmented ink clogs caused by the ink color particles falling out of suspension (i.e., flocculation) or the carrier fluid evaporating off leaving the ink color particles behind. Moreover, the ink delivery channel associated with the screen filter/tower fluid interconnect is not susceptible to clogging caused by pigmented ink viscous plugs as a result of liquid bridging. In addition, the filter/tower fluid interconnect of the present invention substantially prevents pigmented ink drooling (i.e., leakage) when the separable ink delivery components are disconnected. Moreover, the filter/tower fluid interconnect of the present invention impedes debris and air bubbles from clogging or otherwise restricting the flow of pigmented ink from an ink reservoir of an ink container to a print element of a printhead. The filter/tower fluid interconnect of the present invention reliably provides these features throughout the useful life of the pigmented ink delivery system components so as to preclude premature replacement of these components and the associated cost. Lastly, the filter/tower fluid interconnect of the present invention is relatively easy and inexpensive to manufacture, and relatively simple to incorporate into components used in pigmented ink delivery systems of thermal inkjet printing systems.